To overclock the ATI Radeon HD 3870 graphics card, we used ATI Overdrive that is part of the CATALYST Control Center. When you ‘unlock’ the ATI Overdrive, you can manually set the clock and memory settings or let the ‘auto-tune’ utility to set the frequencies for you. Just for fun, I tried out the auto-tune feature to see if it could really find a stable clock configuration and it worked in just a few minutes! Let’s see what the two cards can do with CATALYST 8.1 (Sample_R680_xp_vista_8-451-2-080123a) drivers!
We used the ATI Overdrive utility and found that Auto-Tune was unstable and would lock the system up during use. We gave up on Auto-Tune and manually overclocked the card from 825MHz to 855MHz on the core and from 900MHz to 955MHz on the memory. After testing the overclock on games it was found to be stable, but the scores didn’t budge much. In all honesty our 3DMark06 score actually dropped with the above clock settings, so if you overclock be sure to check and make sure it improves performance. ATI will hopefully have ‘Auto-Tune’ fully working in upcoming driver releases.